Association of social factors and health conditions with capacity and performance

ABSTRACT OBJECTIVE Determine and measure the association of social factors and health conditions with worse capacity and performance levels. METHODS Dependent variables consisted of performance and capacity; independent variables comprised age, gender, level of education, personal income, and health conditions. Means (95%CI) of performance and capacity were presented according to the independent variables. Generalized linear models, using a mutual adjustment for all variables considered statistically significant (p < 0.05), measured the associations between each exposure and outcomes. Study population included 12,265 individuals. RESULTS Older women with lower education and income levels and with some health condition showed the worst performance and capacity. CONCLUSION Results showed that the capacity and performance levels of the Chilean population changed according to social demographic characteristics and health conditions.


INTRODUCTION
One of modern society's fundamental goals is to achieve higher levels of health and wellbeing in the population 1 . As most non-communicable health conditions are non-lethal, in addition to morbidity and mortality, functioning contributes by measuring the impact of health conditions and the outcome of interventions and health promotion 2 .
relationships, handling stress, communication, cognition, household tasks, community and citizenship participation, caring for others, and work and schooling 5 . The survey is answered by a household informant, gathering data via the following sections: socio-demographic characteristics; work history and benefits; environmental factors; functioning; health conditions and capacity; health care utilization; satisfaction, personality and well-being 5 .

Statistical Analyses
Study population characteristics were presented using means or frequencies and their respective 95% confidence interval (95%CI). Means and their respective 95%CI of performance and capacity were presented by social demographic characteristics and health conditions.
We used a generalized linear model (GLM) with logarithmic linkage and gamma distribution to measure differences between categories of outcome explanatory variables due to variable distribution. Our choice of a GLM instead of a linear regression model with logtransformed response was due to the simplicity and greater interpretative understanding of GLM parameters. GLM uses the arithmetic means ratio (AMR) and its respective 95%CI to compare categories of the same response variable and differences are interpreted as percentages (p-value < 0.05).
Weighted sampling was calculated using the survey module (svy command) of the Stata program.

RESULTS
In our study population (n = 12,265), the mean age was 46.47 years (95%CI: 45.98-46.96). Mean capacity score was 27.13 (95%CI: 26.67-27.56), while performance was 34.14 (95%CI: 33.65-34.64). Table 1 summarizes the socio-demographic characteristics and health conditions of the sample. The study population comprised mainly people under 58 years of age with an intermediate educational level, a slightly higher number of women, and frequent reports of the following health conditions: hypertension, LBP, arthrosis, and headache. Table 2 shows the means for capacity and performance scores by sociodemographic characteristics and health conditions. Older women with low education and income levels and with any of the health conditions studied had the worse overall capacity and performance. Table 3 presents the associations of sociodemographic characteristics and health conditions with capacity and performance. Adjusted GLM analyses showed that people over 77 years of age have a mean 68% higher capacity score and 37% higher performance score when compared to people under 38 years of age; women have a mean 13% higher capacity score and 9% higher performance score when compared to men; illiterate people had an mean 51% higher capacity score and 31% higher performance score when compared to those with higher education level; people at the worst income level had a mean 11% higher capacity score and 11% higher performance score when compared to those at the highest income level. Having dementia resulted in a mean 45% higher capacity score and 25% higher performance score; cerebral palsy showed a mean 71% higher capacity score and 42% higher performance score; LBP presented a mean 25% higher capacity score and 21% higher performance score. Among the health conditions studied, hypertension had the least impact on mean capacity (13%) and performance (8%) scores.

DISCUSSION
This study highlights that being an older women with low education and income levels, and having hypertension, arthrosis, respiratory diseases, LBP, headache, anxiety, dementia, CKD, rheumatic diseases, cerebral palsy and sleep disorders were associated with worst capacity and performance. According to the ICF, personal factors influence functioning and are therefore paramount for understanding health and functioning profiles 6 . Similarly, gender, level of education and personal income are considered social determinants of health 3 and have reported influence on the occurrence of disabilities 18,19 . Regarding the Chilean population under study, we found that women had the worst capacity and performance, which generally worsened as education and income decreased. These findings further emphasize the relationship between poverty and disability (expressed here by capacity and performance), emphasizing that disabilities can stem from poverty and vice versa, placing the person with disability in a vicious cycle where poverty leads to more disability, which leads to more poverty 20 . Hence, not only health policies but also social policies can positively impact the population's functioning.
Since research on disability has consistently shown worse disability rates among women worldwide 18 , policies aimed at providing social protection and health services to women could also be effective in improving disability rates in the population. This study also confirmed the association between the aging process and worsening functioning 19 , expressed here by the directly proportional increase in the mean capacity and performance scores with age.
Interviewees with health conditions showed deteriorated capacity and performance.
Research shows that hypertension is associated with disabilities due, in part, to behavioural risk factors such as obesity, smoking, and physical inactivity 21 . Cognitive mechanisms may also be involved in the occurrence of disabilities in hypertensive individuals, since cognitive impairment could lead to less than optimal or poor lifelong decisions, allowing for the appearance or worsening of disabilities 22 .
Arthritis/arthrosis, in turn, implies limitations resulting from pain 23 . Disability is also associate with respiratory diseases, possibly due to muscle strength, lower extremity function, exercise performance, and mobility-related dyspnea 24 . LBP is associated with limitation of activities such as personal hygiene, household chores, and carrying shopping bags due to movement limitations 25 . Migraine is also associated with disabilities, probably caused by pain intensity, attack duration, and number of migraine symptoms 26 . The association between anxiety and disability may be explained by the anxiety response caused by exposure to diverse social situations, panic attacks, and agoraphobia 27 .
Moreover, individuals with dementia are more likely to develop disabilities than others, as this health condition is highly stigmatizing and affects cognitive and independent living skills 28 . Besides physical conditions, socioeconomic, environmental, and individual factors, comorbidities and complications are also associated with higher disability rates in individuals with CKD 29 . As for rheumatic diseases, being an older women who underwent joint surgery and experience pain is associated with disabilities 30 . Cerebral palsy is a very disabling health condition and probably results from motor impairments caused by brain lesions and environmental factors 24 . Finally, sleep disorders are also a predictor of disabilities and this association seems to be indirectly linked to muscle fatigue, which leads to low levels of physical activity, deregulation of systems such as inflammatory, and increased risk of obesity. Importantly, fatigue, overactive inflammatory processes, and obesity are risk factors for disabilities 31 .
As mentioned above, age, gender, level of education, personal income and health conditions are related to increasing occurrence of disability, but the impact of each variable on capacity and performance remains to be discussed. Those aged 38 to 57, 58 to 77, and 78 to 97 years had, respectively, a 20%, 37%, and 68% higher mean capacity score than those under 38 years of age-remembering that the higher the mean, the worse. The performance scores followed a similar pattern, with means of 9%, 17%, and 37%, respectively. Looking at this variable, we see an increasing gradient between the categories, showing a more consistent relationship, with steadily increasing differences in mean capacity and performance scores when related to the reference category.
In the studied population, women averaged 13% higher than men in capacity scores and 9% higher in performance. Regarding level of education, the most significant association was found among those with incomplete primary education and illiterates, with 17% and 51% higher mean capacity scores and 15% and 31% higher mean performance scores, respectively.
As for income, the means showed little difference between categories. Adopting the highest quintile (V) as reference, we found a higher mean capacity score of 4% for quintile V, 6% for quintile III, 12% for quintile II, and 11% for quintile I. For the performance scores, the values were 5%, 7%, 11%, and 11%, respectively.
In practice, determining these associations allows us to estimate the mean capacity and performance scores according to each person's profile. For example, a 56-year-old illiterate woman with lower income suffering from hypertension and LBP will have a 133% higher mean capacity score and 89% higher mean performance score than a 35-year-old man with higher income and no comorbidities. Moreover, such data could be used as a strategy to check the profiles with the highest risk of worsening capacity and performance, pointing out the elements or variables that matter most in worsening functioning.
Although restricted to a representative sample from one country (Chile), this study stands out for bringing to light the discussion about the impact social determinants of health have on capacity and performance. This debate is worldwide and, as the results found here show, should also be applied to the field of disability studies. Would social variables have the same impact on the health of individuals with and without disabilities? Could interventions that seek to address social inequalities be the same for individuals with and without disabilities? These are some of the questions that arise when we verify associations of social variables with worse capacity and performance scores and that should be addressed in future studies.
Moreover, the health conditions studied present an interesting perspective of their association with lower levels of capacity and performance. After adjustments in the statistical analysis process, dementia and cerebral palsy had the highest impact while hypertension proved to be the health condition with the lowest impact among those under study. Our findings stand out for outlining the profile of the population groups that would most need health care aimed at improving capacity and performance. This could have a major individual and collective impact by producing health services and policies targeting these population groups, using interventions designed specifically for such health conditions. The influence of other health conditions on capacity and performance could also be the target of interventions, but without the same urgency and scope as dementia and cerebral palsy.
Although self-reported health conditions are the main limitation of this study, the scientific literature has already discussed the value and importance of collecting self-reported population data 32 . Conversely, its strengths are fivefold. The first and most innovative concerns the quantitative approach to the impact that the studied variables have on capacity and performance. Second, functioning was studied according to definitions established by the WHO. Third, capacity and performance were self-reported, meaning that the collected measurements are person-centered. Fourth, the lack of literature on capacity and performance at the populational level highlights a gap in scientific information that this article hopes to bridge. Lastly, the database derives from a population survey with a complex and reliable sample specifically designed to verify the proposed objectives.
The present study also addresses Article-31 of the Convention on the Rights of Persons with Disabilities (CRPD) regarding statistics and data collection, providing population data collection that enables the formulation and implementation of policies aimed at ensuring the CRPD 33 . Moreover, our research also addresses some of the Sustainable Development Goals (SDG) of the United Nations 2030 Agenda for Sustainable Development 34 that may be directly relevant to people with disabilities. Goal 4 -ensure inclusive and equitable quality education and promote lifelong learning opportunities for all: since our study confirms that people with lower educational level have compromised capacity and performance, the need for policies targeting education inequality is more evident. Goal 5-achieve gender equality and empower all women and girls-is directly related to our results, considering that women had the worse results. Issues involving income are relevant since lower income implies worse results and Goal 8 posits to "promote sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all." Our results clearly present inequalities according to the studied variables, which dialogues with Goal 10: "Reduce inequality within and among countries." These arguments highlight the importance of this study from both a local (the country) and global perspective, as it confirms and reinforces what the United Nations presents as goals for the associated countries via the SDGs. Collection and production of population data on disability using MDS is in line with both the CRPD and the SDGs. Its use has already been reported in the literature and should be reinforced and encouraged 8 .

CONCLUSION
The capacity and performance of the Chilean population varied with age, gender, level of education, income, and self-reported health conditions or chronic diseases. Older women with low income and educational levels were associated with worse capacity and performance scores. Dementia and cerebral palsy were the health conditions that most affected the outcomes studied.
Overall, our results reinforce that areas such as education, income, gender equality and social inequalities, already established by the United Nations as priorities for global sustainable development in the associated countries, should also be the target of specific policies aimed at improving the living and health conditions of persons with disabilities.